http://confocal-microscopy-list.275.s1.nabble.com/FLIM-FRET-tp591029p591033.html
> Search the CONFOCAL archive at
>
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal>
> Thank you Mario and David for the clarifications. I am probably
> overlooking something very trivial, but it is still not clear to me.
>
>
>
> I totally understand that the decay of the total number of excited
> molecules will be faster if there is an additional decaying pathway,
> such as FRET. My question/problem, however, is how this is measured in a
> FLIM experiment? As far as I understand, the photon signal that is
> measured is in fact coming from that subpopulation of excited donor
> molecules which are not FRETting. So in my simple understanding I would
> say that it is till k_f, i.e. relaxation through the fluorescence decay
> pathway, which is selectively being measured and not the decay rate of
> the entire population of excited molecules.
>
>
Think of it this way -- that subpopulation that is not FRETting does not consist
of a fixed population of molecules. Rather -- it consists of those molecules
them. So what you see are those potential donors that emit quickly -- the others
have lost their energy to the acceptors and will never be seen in the donor channel.